Fluid pumping systems are currently used in a wide variety of applications. In some cases, the fluid pumping systems include a pump head that is driven by a rotary motor, such as an internal combustion engine, a hydraulic motor or an electric motor. When driven by the motor, the pump head often produces a pressurized fluid stream that can be used in any number of applications. One illustrative application is that of a high pressure washing device. High pressure washing devices typically deliver a fluid such as water under relatively high pressure to a surface to be cleaned, stripped or prepared for other treatment. Such pressure washers are produced in a variety of designs and can be used to perform numerous functions in industrial, commercial and home applications.
Fluid pumping systems can be either stationary or portable. Stationary fluid pumping systems are generally used in industrial or commercial applications such as in car washes, manufacturing facilities, or the like. Portable fluid pumping systems may include a motor/pump unit that can be carried or wheeled from place to place.
In some cases, fluid pumping systems use a piston pump having one or more reciprocating pistons for delivering liquid under pressure to the pump outlet. Such piston pumps often have two or more pistons to provide a generally more continuous pressure, higher flow rate, and greater efficiency. Multiple piston pumps often use articulated pistons, or may use a swash plate and linear pistons for pumping the liquid. Other pump designs may also exist.
In many cases, power from the motor is transferred to the rotating input shaft of the pump via one or more belts, gears, or the like. However, the use of belts, gears or the like can consume significant energy, thereby reducing the power that is actually delivered and available to the pump. Thus, to achieve a desired pumping capacity, the motor may have to be driven harder, or a larger motor may have to be provided. This can increase the cost of operating the fluid pumping system. In addition, the use of belts, gears or the like can require significant maintenance, which may also increase the cost of operating the fluid pumping system.
One approach to overcome some of these limitations is to drive the rotating input shaft of the pump directly from the rotating drive shaft of the motor. In some cases, both the motor and the pump are attached to a common substrate with the rotating drive shaft of the motor connected directly to the rotating input shaft of the pump. However, in such systems, the mechanical alignment of the shafts, and the ease with which such alignment may be obtained, are of particular concern. The driving and driven shafts may be said to be perfectly aligned when their axes of rotation are coincident with one another at all times. Such perfect alignment would be ideal, but it is often difficult to achieve. In addition, such shaft misalignments can be static and/or transient. As a practical matter, it is not very economical to hold machining tolerances so closely that shaft misalignments are not of a concern. Shaft misalignment can increase vibration, consume energy, degrade motor and/or pump performance, increase operating noise, accelerate wear and tear as well as have other detrimental effects.